The present invention relates to novel sulfonamides and herbicides containing the same as an effective ingredient.
Many sulfonamide compounds have conventionally been proposed as a herbicide. For example, Japanese Patent Publication No. 56-8027 (1981) discloses N-methyl-N-.alpha., .alpha.-dimethylbenzylbenzenesulfonamide. The present inventors have proposed N-(2,3-epoxypropylene)-N-aralkylsulfonamides such as N-(2,3-epoxypropylene)-N-.alpha.-methylbenzylbenzene sulfonamide [Japanese Patent Application Laid-Open (KOKAI) No. 58-131977 (1983)] and N-[2-(pyridyl)propyl]-N-substituted sulfonamide (Japanese Patent Application Laid-Open (KOKAI) Nos. 63-215669 (1988) and 63-222158 (1988)) as a selective herbicide. Japanese Patent Application Laid-Open (KOKAI) Nos. 57-32267 (1982) and 61-286366 (1986) disclose sulfonamides having a pyridyl group as a compound having a herbicidal activity or a fungicidal activity.
An object of the present invention is to provide a herbicide which has a higher herbicidal activity than conventional sulfonamide compounds and a continuous herbicidal activity on weeds such as Echinochloa crus-galli over a long period extending from preemergence to an advanced stage of growing.
As a result of the studies undertaken by the present inventors, it has been found that a sulfonamide represented by the following formula (I): ##STR2## wherein A represents a phenyl group which may be substituted, B represents a phenyl group which may be substituted, R represents a lower alkyl group, a lower alkoxy group or a lower haloalkyl group, W represents a hydroxyl group or a halogen atom, and Z represents a halogen atom, a lower alkylsulfonyloxy group which may be substituted, or a phenylsulfonyloxy group which may be substituted, has a very strong herbicidal effect on Echinochloa crus-galli from preemergence to an advanced stage of growing and cause little damage to paddy-rice plants. On the basis of this finding, the present invention has been achieved.